In the printing industry there is a trend toward operating presses at higher and higher speeds and with a variety of different coatings for application on moving substrates. It is recognized that one of the variables for curing such coatings is the application of ultraviolet radiation. Too little ultraviolet radiation, of course, requires a longer curing time, and an excessive amount of heat, which is a byproduct of mercury vapor lamps used for ultraviolet radiation, may create warping and distortion of the coating on the substrate, and contribute, under certain conditions, to fire and equipment problems. The most common device for such heating or curing purposes is a medium pressure mercury vapor ultraviolet lamp which operates at about two atmospheres of pressure and at about 300 watts per inch, although such lamps may operate between 200 to 400 watts per inch. Such lamps typically have an operating temperature of between about 1100.degree. F. to 1500.degree. F. and are used in conjunction with reflectors which direct the ultraviolet light toward the coated substrate that is to be cured. Lamp-reflector assemblies require cooling to operate most effectively and with a minimum of problems, and the cooling must be accomplished under different press operating conditions.
Air, alone or with water, is the usual medium for cooling lamp reflector assemblies. Most commonly air for cooling such assemblies is provided by low pressure, large-volume blowers which operate between about 1/8 to 1/4 psi. and provide between about 350 to 1500 cfm. The large-volume blowers generate large amounts of air which must be exhausted from the presses and further create large amounts of undesirable ozone which also must be exhausted in a controlled manner from the vicinity of the presses. Occasionally, air for cooling is supplied from a plant compressed air system which has a blower that operates at high pressure and low volume, i.e. about 60 to 80 psi. or higher, and at about 8 to 10 cfm. High pressure air directed through small ports at ultraviolet lamps causes non-uniform cooling of the lamp-reflector assemblies. While both such types of blowers are not restricted in size as they are mounted away from the press equipment, both the low pressure, large volume blower and the high pressure, low volume blower require lamp-reflector assemblies of such a size that they cannot be installed, reasonably, either between the stands of a multi-stand press or in the delivery section thereof, without extensive and expensive modifications to the press equipment.